1. Technical Field
The present disclosure relates to methods for making metal-based composite materials, and particularly relates to a method for making metal-based nano-composite material.
2. Description of Related Art
Metal-based composite materials have wide applications in aviation, vehicles, and information technology for the good specific strength, specific stiffness, abrasion resistance, and high temperature resistance. The performance of the metal-based composite material relates to a size of reinforcements dispersed in the metal-based composite material. Nano-sized reinforcements with a small amount can greatly improve the performance of the metal-based composite material. However, the small size of the nano-sized reinforcements makes the surface energy and surface tension of the nano-sized reinforcements very high. Thus, the nano-sized reinforcements tend to aggregate with each other and are very difficult to be uniformly dispersed in the metal-based material. Stir casting is a conventional technology for preparing metal-based composite material containing relatively large sized reinforcements. However, when using the stir casting method to prepare metal-based nano-composite material, the nano-sized reinforcements are hardly dispersed in the metal material, and are prone to be aggregated and clustered together.
Ultrasonic processing can disperse the reinforcements at a local place in the metal material. During the ultrasonic processing, an amplitude transforming rod is inserted into a mixture of the melt metal and the reinforcements. The end of the amplitude transforming rod can conduct an ultrasonic vibration to the mixture. An ultrasonic vibration can disperse the reinforcements adjacent to the end of the rod. However, when the amount of the mixture is large, the reinforcements away from the end of the rod cannot be sufficiently dispersed. By using this method, serious clustering and aggregation of the nano-sized reinforcements can be found in the composite material especially when the amount of the composite material is larger than 10 kilograms. The non-uniform dispersion of the nano size reinforcements greatly deteriorates the performance of the composite material.
What is needed, therefore, is to provide a method for making a metal-based nano-composite material by which a great quantity of material can be processed simultaneously while nano-sized reinforcements can be dispersed uniformly.